Three-dimensional finite element modelling of all-ceramic restorations based on micro-CT.

OBJECTIVES To describe and apply a method of modelling dental crowns and three-unit fixed partial dentures (FPD) for finite element analyses (FEA) from 3D images obtained using a micro-CT scanner. METHODS A crown and a three-unit fixed partial denture (FPD) made of a ceramic framework (Y-TZP) and veneered with porcelain (VM9) were scanned using an X-ray micro-CT scanner with a pixel size of 6.97 μm. Slice images from both structures were generated at each 0.034 mm and processed by an interactive image control system (Mimics). Different masks of abutments, framework and veneer were extracted using thresholding and region growing tools based on X-ray image brightness and contrast. 3D objects of each model were incorporated into non-manifold assembly and meshed simultaneously. Volume meshes were exported to the FEA software (ABAQUS), and the load-generated stress distribution was analyzed. RESULTS FEA models showed great shape resemblance with the structures. The use of non-manifold assembly ensured matching surfaces and coinciding nodes between different structural parts. For the crown model, tensile stresses were concentrated in the internal surface of the core, near to the applied load. For the FPD model, the highest tensile stresses were located in the framework, on the cervical area of connectors and pontic. CONCLUSIONS Valid 3D models of dental crown and FPD can be generated by combining micro-CT scanning and Mimics software, emphasizing its importance as design tool in dental research. CLINICAL SIGNIFICANCE The 3D FEA method described in this work is an important tool to predict the stress distribution, assisting on structural design of dental restorations.

[1]  M. Zwahlen,et al.  A systematic review of the survival and complication rates of all-ceramic and metal-ceramic reconstructions after an observation period of at least 3 years. Part I: Single crowns. , 2007, Clinical oral implants research.

[2]  P. Cattaneo,et al.  Mechanical behavior of ceramic veneer in zirconia-based restorations: a 3- dimensional finite element analysis using microcomputed tomography data. , 2011, The Journal of prosthetic dentistry.

[3]  Jason A Griggs,et al.  Adaptation of all-ceramic fixed partial dentures. , 2011, Dental materials : official publication of the Academy of Dental Materials.

[4]  J R Kelly,et al.  Clinically relevant approach to failure testing of all-ceramic restorations. , 1999, The Journal of prosthetic dentistry.

[5]  E. D. Rekow,et al.  Factorial analysis of variables influencing stress in all-ceramic crowns. , 2006, Dental materials : official publication of the Academy of Dental Materials.

[6]  M. Zwahlen,et al.  Comparison of survival and complication rates of all-ceramic and metal ceramic reconstructions - A systematic review: Part I. Single crowns , 2007 .

[7]  P. Wilson,et al.  Fracture strength of all-ceramic crowns with varying core elastic moduli. , 2000, Australian dental journal.

[8]  Albert J Feilzer,et al.  The influence of design parameters on the FEA-determined stress distribution in CAD-CAM produced all-ceramic dental crowns. , 2005, Dental materials : official publication of the Academy of Dental Materials.

[9]  E. D. Rekow,et al.  Thermal/mechanical simulation and laboratory fatigue testing of an alternative yttria tetragonal zirconia polycrystal core-veneer all-ceramic layered crown design. , 2010, European journal of oral sciences.

[10]  S. Scherrer,et al.  The fracture resistance of all-ceramic crowns on supporting structures with different elastic moduli. , 1993, The International journal of prosthodontics.

[11]  Irena Sailer,et al.  A systematic review of the survival and complication rates of all‐ceramic and metal–ceramic reconstructions after an observation period of at least 3 years. Part II: fixed dental prostheses. , 2007 .

[12]  H Fischer,et al.  Lifetime Prediction of All-ceramic Bridges by Computational Methods , 2003, Journal of dental research.

[13]  Vince Adams,et al.  Building Better Products with Finite Element Analysis , 1998 .

[14]  P. Petsche,et al.  Influence of glass-ceramic thickness on Hertzian and bulk fracture mechanisms. , 1998, The International journal of prosthodontics.

[15]  Hideaki Takanobu,et al.  Study of finite element modeling from CT images. , 2005, Dental materials journal.

[16]  Pascal Magne,et al.  Efficient 3D finite element analysis of dental restorative procedures using micro-CT data. , 2007, Dental materials : official publication of the Academy of Dental Materials.

[17]  D. Watts,et al.  Sequential software processing of micro-XCT dental-images for 3D-FE analysis. , 2009, Dental materials : official publication of the Academy of Dental Materials.

[18]  J. Quinn,et al.  Failure analysis of ceramic clinical cases using qualitative fractography. , 2006, The International journal of prosthodontics.

[19]  Martin Rosentritt,et al.  Approach for valuating the influence of laboratory simulation. , 2009, Dental materials : official publication of the Academy of Dental Materials.

[20]  S. Bayne,et al.  Stress concentration in all-ceramic posterior fixed partial dentures. , 1996, Quintessence international.

[21]  Alvaro Della Bona,et al.  The slippery slope: critical perspectives on in vitro research methodologies. , 2012, Dental materials : official publication of the Academy of Dental Materials.

[22]  J A Tesk,et al.  Failure of All-ceramic Fixed Partial Dentures in vitro and in vivo: Analysis and Modeling , 1995, Journal of dental research.

[23]  J. Quinn,et al.  Fractographic analyses of three ceramic whole crown restoration failures. , 2005, Dental materials : official publication of the Academy of Dental Materials.

[24]  H. Schienbein.  [Dental radiographic equipment past and present (II)]. , 1976, Die Quintessenz.

[25]  V. Rousson,et al.  Recommendations for conducting controlled clinical studies of dental restorative materials , 2007, Clinical Oral Investigations.

[26]  Luigi Nicolais,et al.  A 3D analysis of mechanically stressed dentin-adhesive-composite interfaces using X-ray micro-CT. , 2005, Biomaterials.

[27]  K. Anusavice,et al.  Fracture Surface Characterization of Clinically Failed All-ceramic Crowns , 1994, Journal of dental research.

[28]  E Y Chao,et al.  A survey of finite element analysis in orthopedic biomechanics: the first decade. , 1983, Journal of biomechanics.

[29]  J. Griggs,et al.  Flexural strength and failure modes of layered ceramic structures. , 2011, Dental materials : official publication of the Academy of Dental Materials.

[30]  N H F Wilson,et al.  Finite element analysis of fixed partial denture replacement. , 2004, Journal of oral rehabilitation.

[31]  Michel Barquins,et al.  Relevance of the finite element method to optimize fixed partial denture design , 1998, Clinical Oral Investigations.

[32]  Kenneth J Anusavice,et al.  Viscoelastic finite element analysis of an all-ceramic fixed partial denture. , 2006, Journal of biomechanics.

[33]  J. D. Brewer,et al.  Effect of two connector designs on the fracture resistance of all-ceramic core materials for fixed dental prostheses. , 2009, The Journal of prosthetic dentistry.

[34]  N Verdonschot,et al.  Generation of 3-D finite element models of restored human teeth using micro-CT techniques. , 2001, The International journal of prosthodontics.

[35]  P. Magne.  Virtual prototyping of adhesively restored, endodontically treated molars. , 2010, The Journal of prosthetic dentistry.

[36]  F. Burke.  Fracture resistance of teeth restored with dentin-bonded crowns: the effect of increased tooth preparation. , 1996, Quintessence international.

[37]  Josef Schweiger,et al.  High-strength CAD/CAM-fabricated veneering material sintered to zirconia copings--a new fabrication mode for all-ceramic restorations. , 2009, Dental materials : official publication of the Academy of Dental Materials.

[38]  A Imanishi,et al.  3-D Finite element analysis of all-ceramic posterior crowns. , 2003, Journal of oral rehabilitation.

[39]  E. D. Rekow,et al.  Design features of a three-dimensional molar crown and related maximum principal stress. A finite element model study. , 2010, Dental materials : official publication of the Academy of Dental Materials.

[40]  R. P. Christensen,et al.  A clinical comparison of zirconia, metal and alumina fixed-prosthesis frameworks veneered with layered or pressed ceramic: a three-year report. , 2010, Journal of the American Dental Association.

[41]  Won-Suck Oh,et al.  Effect of connector design on the fracture resistance of all-ceramic fixed partial dentures. , 2002, The Journal of prosthetic dentistry.

[42]  B. Melsen,et al.  The Finite Element Method: a Tool to Study Orthodontic Tooth Movement , 2005, Journal of dental research.

[43]  N Wakabayashi,et al.  Nonlinear finite element analyses: advances and challenges in dental applications. , 2008, Journal of dentistry.

[44]  F. Wong,et al.  X-ray microtomography of bones and teeth. , 1996, Physiological measurement.

[45]  Uwe Wolfram,et al.  A downloadable meshed human canine tooth model with PDL and bone for finite element simulations. , 2009, Dental materials : official publication of the Academy of Dental Materials.

[46]  A. Kato,et al.  Construction of three-dimensional tooth model by micro-computed tomography and application for data sharing , 2009, Clinical Oral Investigations.

[47]  K. Kunzelmann,et al.  Mineral concentration of natural human teeth by a commercial micro-CT. , 2006, Dental materials journal.

[48]  K A Malament,et al.  Survival of Dicor glass-ceramic dental restorations over 14 years. Part II: effect of thickness of Dicor material and design of tooth preparation. , 1999, The Journal of prosthetic dentistry.

[49]  Stephen Bayne,et al.  Recommendations for conducting controlled clinical studies of dental restorative materials. Science Committee Project 2/98--FDI World Dental Federation study design (Part I) and criteria for evaluation (Part II) of direct and indirect restorations including onlays and partial crowns. , 2007, The journal of adhesive dentistry.

[50]  Yang-Jin Yi,et al.  Effect of occlusal contact size on interfacial stresses and failure of a bonded ceramic: FEA and monotonic loading analyses. , 2008, Dental materials : official publication of the Academy of Dental Materials.

[51]  J. J. Mecholsky,et al.  Fractographic analyses of zirconia-based fixed partial dentures. , 2008, Dental materials : official publication of the Academy of Dental Materials.

[52]  G. Thompson.  Influence of relative layer height and testing method on the failure mode and origin in a bilayered dental ceramic composite. , 2000, Dental materials : official publication of the Academy of Dental Materials.